Shallow sand bed and passing gas....

Electrobes · Mar 17, 2016

Sorry y'all, I couldn't help myself.

So I have a shallow 1" sand bed using Reefflakes 3mm grain sand. Having revamped my tank about three months ago, I've always vacuumed my sand bed (With an Eheim gravel vac), about once a week.

As of late, I've noticed the sand bed gassing off, what I assume to be Nitrogen by Anaerobic bacteria via de-nitrification. If this is true, should I not be sand vacuuming? Should I instead leave the sand bed be.. or does sand vacuuming not disturbed the bacteria? My only thought is that I do remove organic matter from the sand bed (It's either caught or tossed into the water column)... which I believe it to be a consumable of the bacteria... I think.

My basic tank specs (100G total water volume), should it help any:

- Skimmer doubly rated for my size tank.
- Carbon dosed via Vinegar (55mL per day)
- I do add BioDigest once weekly (Bacteria addition)
- 4L of Matrix (I have very little rock in my display.. four pieces)
- I complete a 10% water change weekly (Via AF Reef Salt, not the Probiotic stuff).
- I feed about three cubes of frozen food, for 11 fish, about half are medium sized fish.

fragit · Mar 17, 2016

It's my understanding that anaerobic bacteria will not live in a sand bed that shallow. Oxygenated water will penetrate through the sand. As for the gas bubbles I have no idea what would cause that in a SB that shallow. Are you having any Algea issues? Is the sand new?

Electrobes · Mar 17, 2016

fragit said:
It's my understanding that anaerobic bacteria will not live in a sand bed that shallow. Oxygenated water will penetrate through the sand. As for the gas bubbles I have no idea what would cause that in a SB that shallow. Are you having any Algea issues? Is the sand new?

I have absolutely zero algae issues in my tank, even with my surprise test results two days ago. Lemme see if I can pull it up...

Electrobes · Mar 17, 2016

Electrobes · Mar 17, 2016

Randy Holmes-Farley · Mar 17, 2016

Can you describe when and how you see the bubbles?

Electrobes · Mar 17, 2016

They form within the sand bed, not on the top. I can see it through my tank wall. When I vacuum the sand, I get bubbles that get knocked loose from within all the time I vacuum. Here is my poor attempt at a picture.

Electrobes · Mar 17, 2016

The bubbles you see at the very bottom is part of the acrylic.. It's a design of the tank, ignore that.

Randy Holmes-Farley · Mar 17, 2016

Try watching them over the next couple of days and see if they seem more prevalent at the beginning or end of the light cycle.

It might be N2, but it may also be O2.

ed wicks · Mar 17, 2016

Tank clean looking,your fish have nice colors,nice and healthy.

FoxyFace · Mar 17, 2016

It's nitrogen.

brandon429 · Mar 17, 2016

it is surely better for your tank to keep it in this condition, that clean, vs let detritus compile in that larger grain bed to try and boost denitrification.

if allowing better denitrification via more hands off approach would lessen your export work it might be considered, but denitrification yes/no in that shallow bed wont make up for what your skimmer or water changes or algae filters or binding media does so I say hold course keep doing what you are doing. A tank that size/dilution will let you get away with most actions for a few years anyway, its the long term scope I was considering

BigMack · Mar 17, 2016

Electrobes said:

what app are you using for test results?

Electrobes · Mar 17, 2016

That's Aquarimate. It also does reminders. I love it!

brandon429 · Mar 17, 2016

Check out Paul Bs article in gen forum on OTS I liked it and it's a total tie to this thread. Your sand grain size here is not good or bad, it has different characters that's all but it factors in the ideal care for your tank as it ages in my op
Nice pics

My powder fine oolite deep sand bed of six inches concentrates detritus up top, it doesn't allow speedy work down into the bed, there is time to siphon the edges of the tank and maybe a sixteenth of an inch into the bed for detritus removal. By design I wanted it that way

But my trade off is if I get lazy, I can't siphon down two inches into the bed they don't make a fitting for that, all oolite will come up.

You have large grains/incursion large particle interstitial spaces

Your bed penetration is orders faster and orders more accessible without tearing your tank down to have to truly clean the bed, which I do.

The opposite of any of this is the decades old practice of hands off sandbedding, that doesn't seem to be working for the masses but I'm aware of one off examples. The OTS article addresses causatives well in my opinion

One thing is for sure, the longest living reef tanks from each genre of reefing are addressing detritus in some direct way, while the hands off modes comprise just the outliers not the bulk where age is found

The more gallons of water in a reef tank, the easier it is to claim that hands off constant storage and internal breakdown of waste is best.